As a conventional failure determination device for a shutter device of a vehicle of this kind, one described e.g. in PTL 1 is known. A radiator is disposed in an engine room of a vehicle, and in a front opening, a grille shutter is disposed for feeding ambient air for cooling the radiator. If a detected temperature of coolant in the engine (hereinafter referred to as “engine coolant temperature”) is not lower than a predetermined temperature, the grille shutter is opened, and if it is lower than the predetermined temperature, the grille shutter is closed. With this, the amount of ambient air introduced into the engine room is controlled according to the engine coolant temperature, whereby the radiator is maintained at an appropriate temperature.
Further, in this failure determination device, when the engine coolant temperature at the time when a predetermined time has elapsed after the command to the grille shutter is switched from a closing command to an opening command is not lower than a first predetermined temperature A0, the engine coolant temperature has not lowered, and hence it is determined that the grille shutter is stuck on the closed side. Further, if the engine coolant temperature at the time when the opening command is continuously output to the grille shutter is higher than a second predetermined temperature B which is higher than the first predetermined temperature A0, it is too high for the engine coolant temperature to be assumed when the grille shutter is open, so that it is also determined that the grille shutter is stuck on the closed side.